The present invention relates to an adjusting device of a compressor with guide vanes arranged in the form of a ring around a longitudinal axis, which vanes are in each case fixedly connected to pivot pins to rotate therewith and are pivotally mounted in a housing, with two-armed cranks, which are in each case connected to one of the pivot pins, and with coupling links, which are in each case pivoted at corresponding crank arms of neighboring cranks, wherein the pivot pins and guide vanes are spaced apart in circumferential direction at uniform angular spacings and are jointly adjustable in the same direction.
An adjusting device for an axial-flow compressor is disclosed in U.S. Pat. No. 3,056,541, in which the cranks and the coupling links are arranged concentrically around the longitudinal axis of the axial-flow compressor on a cylindrical circumferential surface. All of the pivot pins of the guide vanes, which are arranged in front of the intake port of the axial-flow compressor, lie in a common radial plane. The cranks arranged cylindrically around the guide vanes are of straight design. In the case of an adjustment, the coupling links between the respectively adjacent cranks are moved along a multidimensional path, so that ball joints are necessary between the cranks and the coupling links. In an adjustment, forces which lie in the three mutually orthogonal directions in space have to be transferred. In view of the three-dimensional movement sequences, even small production inaccuracies can easily lead to faults, or even a jamming of the entire adjusting device. The coupling links are therefore designed to be adjustable in length, as a result of which a not inconsiderable space requirement and production outlay are necessary.
An adjusting device is known from European Pat. No. 43,017which has an adjusting ring arranged concentrically to the longitudinal axis of a radial-flow compressor for effecting common adjustments of the secondary guide vanes. A linkage lever is fixedly connected for rotation with each of the pivot pins and is provided at its other end with a slot. A bolt connected to the adjusting ring engages in this slot. When the adjusting ring is turned about the longitudinal axis of the radial-flow compressor, the pivot pin and the associated guide vane are pivoted via the respective bolt and linkage with the bolt being displaced in the slot. For large diameter radial-flow compressors, for example, devices with impeller diameters of one meter or more, correspondingly large dimensions result for an adjusting ring coaxial to the longitudinal axis. The production and storage of such a large adjusting ring presents considerable difficulties in practice. Furthermore, in view of the large dimensions of the adjusting ring, problems arise with regard to temperature behavior and thermal expansion. The space requirement is considerable, and difficulties arise in handling and assembly. Finally, it cannot be overlooked that in large radial-flow compressors, production and assembly of an adjusting ring coaxial to the impeller axis require a considerable cost outlay.
Furthermore, a device for adjusting swirl vanes of a turbo compressor is disclosed in German published application No. DE 24 03 113. The pivot pins are fixedly connected to rotate with the swirl vanes and each contain a gear wheel at the free end. All of the gear wheels are in engagement with a common adjustable gear ring. Difficulties arise with such a gear ring similar to those encountered with the adjusting ring described above, in particular with regard to thermal stresses, tolerances and cost of assembly. Particularly in relatively large compressors there is a risk of jamming and blocking the vanes.